The literature indicates that caffeine affects males and females differently (Kawachi et al., 1996; Arnold, 1987 & Botella, P., Parra, A. 2003). Females are more vulnerable to the effects of caffeine due to greater hormonal fluctuation, especially during the luteal phase of the menstrual cycle (premenstrual). The goal of this project is to assess the effects of caffeine consumption on premenstrual distress. Participants complete the Daily Rating Form, Self-Rating Scale for Premenstrual Syndrome, and caffeine survey online daily for two consecutive months for diagnostic purposes. Experimenters will decide whether participants meet criteria for PMS-a 30% increase in symptoms during the luteal phase and termination of symptoms at the onset of menses. Subjects are screened for caffeine sensitivity, pregnancy, and history of major depression. At the laboratory session, instructions are given to participants and they are asked to complete the VAS and the Menstrual Questionnaire before the administration of caffeine pills (300mg) or placebo pills. Participants then perform a mirror tracing task. At the termination of the experiment, there is opportunity to address concerns and questions about the project and get debriefed.